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18% Fokker-D23 Project. HELP

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Old 01-04-2007, 05:58 PM
  #1
Bad Dawg
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Default 18% Fokker-D23 Project. HELP

After more than a decade of procrastinating I am going to build an 18% Fokker D-23. It was Anthony Fokker's last fighter design. I am working from Fokker Heritage Trust original photos, drawings and plans (For which, I am in debt to Rob Ercavich (sp?). A Dutch modeler. Thanks Rob.)

http://www.dutch-aviation.nl/index5/...5-1%20D23.html

This is the largest model I have attempted and I expect the learning curve to be considerable. Those of you with experience in scratch building large scale can be a great help in keeping me out of dead ends. Please help?

The basics:
Wing; 82" span, 995 sq in. 22% nearly symetrical root, 16% semi-symetrical tip (from Fokker blue prints)
LOA 71" Twin boom, Pusher/ Puller
Powered by two four stroke pumped engines
basic construction is glass coated, balsa sheeted foam (8 yr.s of combat foamie construction experience. One of the few things I know how to do.)
6 ch. and 11 to 14 servos depending on gear door actuation.
Pretty close on to 150 oz of gear in it (engines, servos, retracts, batteries & etc.)
I am using TurboCadLE (2D)to draw the plans.
Now for the first few of many questions.

Would anyone care to venture the all up weight range?

I have a good YS 120 kicking around the shop. Would a pair of those be too much, to little or just about right?

I tried to attach the first rough draft of the plans but RCU doesn't "support" TurboCad's format. Well this could get wordy.

Thanks In Advance
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Old 01-05-2007, 11:36 AM
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Chad Veich
 
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Default RE: 18% Fokker-D23 Project. HELP

Sounds like a fantastic project, I love the out-of-the-ordinary stuff. Not knowing a great deal about how you build and finish it's hard to estimate what the all up weight would be. Most models in this size range probably fall into the 18-25 pound category, though guys like Brian Taylor could probably build it at 15 pounds! I would probably shoot for an all up weight of not more than 20 pounds, or around 46 oz per sq/ft wing loading. That should make for a nicely flyable model that would perform better than scale on two YS 1.20 motors. That's my .02 cents anyway, good luck with it.

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Old 01-05-2007, 09:49 PM
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Bad Dawg
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Default RE: 18% Fokker-D23 Project. HELP

Thank you, Chad. I needed an outside estimate. I was thinking 18#, but I don't have the experience building or flying this size plane to have confidence in my guestimate.
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Old 01-06-2007, 11:12 AM
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Chad Veich
 
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Default RE: 18% Fokker-D23 Project. HELP

I would think that 18# is certainly doable if you are careful with your engineering, material selection, and finishing methods. However, even if you happen to go over by 2-4 pounds I still think you would have an airplane that would perform just fine. (assuming all other factors are good) Looking forward to watching your progress, best of luck with it.

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Old 06-21-2007, 08:22 PM
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Default RE: 18% Fokker-D23 Project. HELP

Hi
I built a D23 back in the 70's which was featured on the cover of Radio Modeller here in the UK. Like your planned build mine was in the 80" region but heres the twist. Mine was powered by two 40's. Front one being a very powerful (for it's day) Webra speed 40 and the rear engine was an Enya 40, which was a bit agricultural. All up weight was around 12-13 lbs. It took about 20 yds to take off on short grass, so I don't think it was that under-powered. Construction was skeleton ply formers and stringers filled in between with soft balsa and then over finished in sheet. Booms and tailplane were almost entirely 1/4 sheet balsa in various densities. My mountings for the re-tracts were a bit weak and broke on the first landing, probably because of the heavy landing in the poor weather and lack of piloting skill. However it was repaired and flew for a season or two. Directional stability was a bit on the poor side because the prop-wash missed the rudders. When I sold the model the guy who bought it set the rudders outwards by about 5 degrees (to induce drag I suppose) and reported that it tightened up its stability a lot (doubtful).
However, it's a great subject to model and I'd be interested to see your results.
Good luck and Happy flying.
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Old 12-10-2007, 08:39 PM
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Default RE: 18% Fokker-D23 Project. HELP

Hi
I got a lot of mail regarding my original D23 (77.75" span) and have decided to build another, which is in progress at the moment. If anyone is interested I have plans and instructions available and hope to be able to supply short kits of laser cut parts in the near future.
Happy flying
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Old 12-11-2007, 02:31 AM
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Default RE: 18% Fokker-D23 Project. HELP

Keeping in mind that I HATE heavy wing loadings you can take this with a grain of salt.....

If you've got two Saito 1.20's I would suggest that you could up the size of the model to something closer to 100 inches and still have enough power for spirited flying manners. As a bonus the extra wing area would help carry the weight more easily and result in a reduced wing loading over the smaller 995 sq inch option. Weight would rise a bit of course since there's more model but even at 20 to 24 lbs it should still climb well I would suspect.

And in light of Mike's posts about his slightly smaller one flying like what sounds like a hotrod on two 40's I don't think my suggestion is out of line.
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Old 04-23-2008, 03:55 AM
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Default RE: 18% Fokker-D23 Project. HELP

I know I am a bit late here but this may be helpful:

http://www.antiqbook.nl/boox/rij/32664.shtml
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